Chapter 37

Question 1

Where do Plants obtain most of their water and mineral from

Answer 1

the upper layers of soil

Question 2

Soil particles are classified by

Answer 2

size; from largest to smallest they are called sand, silt, and clay

Question 3

Topsoil

Answer 3

mineral particles, living organisms, and humus, the decaying organic materials

Question 4

Soil is stratified into layers called

Answer 4

soil horizons

Question 5

The B horizon

Answer 5

has less organic matter and is less weathered than the A horizon

Question 6

The C horizon

Answer 6

mainly partially broken down rock

Question 7

Loams

Answer 7

are the most fertile topsoils and contain equal amounts of sand, silt, and clay

Question 8

Cation Exchange

Answer 8

cations are displaced from soil particles by other cations

Question 9

Topsoil contains

Answer 9

bacteria, fungi, algae, other protists, insects, earthworms, nematodes, and plant roots; help to decompose organic materials and mix the soil

Question 10

Sustainable agriculture

Answer 10

farming methods that are conservation-minded, environmentally safe, and profitable

Question 11

Irrigation

Answer 11

Drains water resources when used for farming in arid regions

Question 12

Fertilization

Answer 12

replaces mineral nutrients that have been lost from the soil

Question 13

Commercial fertilizers:

Answer 13

nitrogen (N), phosphorus (P), and potassium (K)

Question 14

Erosion

Answer 14

topsoil from thousands of acres of farmland is lost to water and wind each year in U.S.; loss of nutrients

Question 15

Erosion can be reduced by

Answer 15

-Planting trees as windbreaks
-Terracing hillside crops
-Cultivating in a contour pattern
-Practicing no-till agriculture

Question 16

Phytoremediation

Answer 16

biological, nondestructive technology that reclaims contaminated areas

Question 17

what contribute to plant growth

Answer 17

Soil, water, and air

Question 18

Macronutrients (9) required in large amounts

Answer 18

C, O, H, N, P, S, K, Ca, & Mg.

Question 19

Micronutrients (8) very small amounts

Answer 19

-Cl, Fe, Mn, B, Zn, Cu, Ni, Mo
-C4 and CAM plants: also Na
-Cofactors: non-protein helpers in enzymatic reactions

Question 20

Flood Tolerance:

Answer 20

waterlogged soils deprive roots of oxygen and cause buildup of ethanol and toxins

Question 21

Plants and soil microbes have a what kind of relationship?

Answer 21

Mutualistic

Question 22

Rhizosphere

Answer 22

soil layer bound to the plant’s roots

Question 23

Rhizobacteria

Answer 23

-Produce hormones that stimulate plant growth
-Produce antibiotics that protect roots from disease
-Absorb toxic metals or make nutrients more available to roots

Question 24

Nitrogen fixation

Answer 24

conversion of N2 to NH3

Question 25

Nodules

Answer 25

swellings along a legume’s roots composed of plant cells “infected” by nitrogen-fixing Rhizobium bacteria

Question 26

Crop rotation

Answer 26

nonlegume, maize, is planted one year, and the next year a legume is planted to restore the concentration of fixed nitrogen in the soil

Question 27

Mycorrhizae

Answer 27

mutualistic associations of fungi and roots

Question 28

Ectomycorrhizae

Answer 28

fungal mycelium forms a dense sheath over root surface

Question 29

Arbuscular mycorrhizae

Answer 29

microscopic fungal hyphae extend into the root

Question 30

Epiphyte

Answer 30

grows on another plant and obtains water and minerals from rain; Spanish Moss